Portable electronic devices may include one or more batteries that may require recharging from time to time. Such devices may include electric vehicles, cell phones, smart phones, tablet computers, laptop computers, wearable devices, navigation devices, sports devices, health analysis devices, medical data devices, location tracking devices, accessory devices, home appliances, peripheral input devices, remote control devices, and so on. As a result of high packing density, high energy density, long cycle life, and ease of mass production, portable electronic devices typically include one or more lithium-polymer or lithium-ion batteries.
Over the operational life of a lithium-polymer rechargeable battery, the internal resistance of the rechargeable battery may increase as a result of oxidation, lithium dendrite growth, cathodic gas evolution, and/or cathodic degradation, due at least in part to repeated charging and discharging of the rechargeable battery. As a result, the power output capacity of the rechargeable battery may decrease over time, undesirably limiting the useful life of the rechargeable battery and/or the portable electronic device. In other examples, non-optimal charging conditions can also effect an increase in internal resistance of the rechargeable battery. For example, the internal resistance of the battery may increase as a result of charging at high voltage, delayed transition from constant current to constant voltage charging, and/or charging or discharging at a high temperature. In many examples, the internal resistance of the rechargeable battery may correlate or correspond to target charge capacity, rechargeable battery health, and/or rechargeable battery age.
In addition, lithium-polymer batteries may physically expand or swell during charging of the rechargeable battery. For example, the anode material can expand substantially over repeated charging cycles or even during a single charging cycle. In other cases, gas emissions from a charged cathode can, over time, result in an expanded rechargeable battery. Over time, the rechargeable battery can expand beyond its allotted volume within the portable electronic device, damaging components and/or portions the portable electronic device. In these cases, a user of a portable electronic device may be entirely unaware of the expansion of the rechargeable battery until conspicuous physical damage occurs.
Accordingly, there may be a present need for a method and system for detecting, arresting, mitigating, and compensating for rechargeable battery expansion.